Lack of delicate feel is normal for thick gloves.
A possible solution:
-buy a pair of 3mm gloves
-on your thick glove (I assume the right one because the shutter release on most housings is on the right), mark between the base of finger and the first joint out from the base on glove's index finger.
-cut off index finger on the thick glove at the mark (make a careful straight cut)
-cut off one of the fingers on the 3mm gloves at the base so you have plenty of adjustment room (you've have 7 spares to use in the future)
-put on your right thick glove
-do test fits and trims of the 3mm finger until you reach the correct length of the new 3mm replacement
-use wetsuit/neoprene glue to attach the 3mm finger to your thick glove
-allow the glue seam to dry completely
-think about doing some careful surface stitching to keep the nylon facing of each part from pulling the seam apart
Take Care,
ChrisS
PS, I use five-finger 4mm skin-in gloves for all my cold water diving (Monterey, SoCal, and BC); I also dive a dry suit.